The present invention relates to a rotor of an electric motor and a manufacturing method thereof.
FIGS. 8 and 9 show a conventional rotor core 50. As shown in FIGS. 8 and 9, the rotor core 50 has a plurality of core sheets 52 laminated one on another. Each core sheet 52 has a plurality of teeth 51 extending radially. A winding 53 is wound on the rotor core 50 by distributed winding after a shaft 54 is inserted into a center hole 56. As a result, the winding 53 is laid out in slots 55 each formed between the teeth 51 adjoining in the peripheral direction. In a case where the winding 53 by distributed winding, however, it is difficult to increase the space factor of the winding in the slots 55.
Accordingly, it is a primary objective of the present invention to provide a rotor of an electric motor which can easily increase the space factor of the winding and a manufacturing method thereof.
To achieve the object, the present invention provides a rotor of an electric motor which is constructed in the following manner. The rotor includes a plurality of first core sheets and a plurality of second core sheets. Each first core sheet includes a plurality of first teeth laid out in a ring form on a first plane. Each first tooth has a first winding portion extending in the radial direction of the rotor and a first arm portion integrally provided at an outer end of the first winding portion in the radial direction of the rotor and extending in the peripheral direction of the rotor. Each first arm portion has a first coupling portion at one end. Each second core sheet includes a plurality of second teeth laid out in a ring form on a second plane. Each second tooth has a second winding portion extending in the radial direction of the rotor and a second arm portion integrally provided at an outer end of the second winding portion in the radial direction of the rotor and extending in the peripheral direction of the rotor. Each second arm portion has a second coupling portion at one end. The first core sheets and the second core sheets are stacked in the axial direction of the rotor. Each first tooth is stacked on an associated one of the second teeth in the axial direction of the rotor. Each first tooth is coupled to that one of the second teeth which is stacked on another one of the first teeth adjoining in the peripheral direction of the rotor by coupling of the first and second coupling portions. A remaining portion of each arm portion, which excludes the associated coupling portion, is located further apart from the axis of the rotor than the associated coupling portion.
The present invention further provides a method of manufacturing a rotor of an electric motor, which comprises the steps of forming a plurality of first teeth and a plurality of second teeth by punching a metal plate, each tooth having a winding portion extending in one direction and an arm portion which is integrally provided at a distal end of the winding portion, said arm portion extending in a direction nearly perpendicular to the winding portion and having a coupling portion at one end, a remaining portion of each arm portion which excludes the associated coupling portion being located further apart from a proximal end of the associated winding portion than the associated coupling portion; forming a plurality of laminated bodies by stacking the first teeth and the second teeth in such a way that the coupling portions of the first teeth and the coupling portions of the second teeth in each laminated body face in opposite directions; forming a coupled body comprised of a plurality of laminated bodies by coupling the coupling portions of the first teeth in one of adjoining two laminated bodies to the coupling portions of the second teeth in the other one of the adjoining two laminated bodies in a rotatable manner, the laminated bodies being laid out in a line in such a way that the winding portions in each laminated body become nearly parallel to the winding portions in another laminated body; winding a winding on the winding 10 portions in each laminated body; and rotating adjoining two laminated bodies in such a way that the coupled body forms a ring-like shape and the winding portions are arranged radially.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.